Roller for moveable objects
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Solution Overview
Problem
Existing anti-rotation devices for castors, such as bed castors, are expensive to produce and prone to wear due to complex geometries and tolerance deviations, with issues exacerbated by the use of plastic components.
Innovation Solution
A cylindrical locking element with a profiled surface that overlaps a hexagonal nut, forming an anti-twist device, allowing for simpler construction and use of plastic materials, with a sliding element like PTFE to mitigate tolerance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hexagonal anti-twist device with turned and cleared contours is used, then anti-rotation function is achieved, but manufacturing cost increases and production complexity increases
Solution Approach 1:
The anti-twist device is segmented into two separate components: a hexagonal securing element (nut) and a profiled locking element. This segmentation allows each component to be manufactured independently using simpler, more cost-effective processes such as injection molding for plastic parts, eliminating the need for complex turning and clearing operations on a single integrated pin.
Solution Approach 2:
The invention employs inexpensive plastic components (locking element and securing element) that can be mass-produced through injection molding. These plastic parts replace expensive metal components requiring complex machining, significantly reducing manufacturing costs while maintaining functional reliability.
2Reliability
If a hexagonal anti-twist device with turned and cleared contours is used, then anti-rotation function is achieved, but device complexity increases
Solution Approach 1:
By dividing the anti-twist mechanism into separate modular components (securing element and locking element), the invention simplifies the overall production process. Each component can be manufactured, inspected, and assembled independently, reducing production complexity compared to manufacturing a single complex integrated pin with turned and cleared contours.
3Ease of manufacture
If tolerance deviations in the guide area are present, then manufacturing is simplified, but angular deflections of the roller increase
Solution Approach 1:
The hexagonal securing element serves multiple functions: it provides the anti-rotation function through its polygonal shape, acts as a locking mechanism, and compensates for tolerance deviations through its geometric design. The profiled locking element with overlapping profile further compensates for tolerances, allowing larger manufacturing tolerances without causing angular deflections.
Solution Approach 2:
The invention uses composite material solutions, particularly plastic components (PMMA, polycarbonate, or polyamide) that combine structural integrity with tolerance compensation capabilities. These materials allow for larger manufacturing tolerances while maintaining functional precision through their inherent flexibility and damping properties.
4Ease of manufacture
If plastic components are used in the anti-twist device, then manufacturing cost decreases, but wear resistance decreases
Solution Approach 1:
The invention specifies using high-quality engineering plastics (PMMA, polycarbonate, or polyamide) that provide adequate wear resistance for the application. These materials can be reinforced with glass fibers or other additives to enhance durability while maintaining cost-effectiveness and manufacturability through injection molding.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective, robust anti-rotation mechanism that compensates for tolerance deviations and allows for the use of commercially available components, enhancing the stability and reliability of the castor system.
Implementation Method 1
a sliding element being able to be provided between the bore and the outer peripheral surface of the cylindrical locking element. This sleeve-like sliding element can, if necessary, consist of a plastic, in particular PTFE.
Data Source
Figure 1
Figure 2~3
AI summary
Castor for movable objects, in particular bed castors, at least containing a running wheel, a fork receiving the same, a guide tube which is designed to be pivotable relative to the fork via at least one bearing, locking means provided on the fork side and a non-rotating brake system which can be brought into operative connection with the running wheel, wherein the braking system includes a substantially cylindrical locking element profiled on one side, which can be brought into operative connection with a polygonal locking element on the fork side to form the anti-twist device, the profile provided on the locking element essentially corresponding to the outer contour of the locking element.